1. Field of the Invention
The present invention relates to a timepiece with a calendar mechanism indicating 1st to 31st days by a first date indicator and a second date indicator. In particular, the present invention relates to a timepiece with a calendar mechanism capable of indicating dates in date letters larger than those of a conventional timepiece with a calendar mechanism.
2. Description of the Related Art
A mechanical structure including a drive portion of a timepiece is generally referred to as a “movement”. What is completed by attaching a dial and hands to the movement and putting the whole in a timepiece case is referred to as the “complete” of the timepiece. Of both sides of a main plate constituting the base plate of the timepiece, the side where the glass of the timepiece case exists, that is, the side where the dial exists, is referred to as the “back side” or “glass side” or “dial side” of the movement. Of both sides of the main plate, the side where the case back of the timepiece case exists, that is, the side opposite to the dial side, is referred to as the “front side” or the “case back side” of the movement. A train wheel incorporated into the “front side” of the movement is referred to as the “front train wheel”. A train wheel incorporated into the “back side” of the movement is referred to as the “back train wheel”.
In the following, the construction of a conventional timepiece with a calendar mechanism including a first date indicator indicating the one place of a date, and a second date indicator indicating the ten place of a date, will be described.
(1) First Type Conventional Calendar Mechanism
A first type conventional calendar mechanism is equipped with a first date indicator indicating the one place of a date, a first date jumper for setting the position in the rotating direction of the first date indicator, a second date indicator indicating the ten place of a date, a second date jumper for setting the position in the rotating direction of the second date indicator, and a date intermediate wheel rotating based on the rotation of the first data indicator and capable of rotating the second date indicator. The first date indicator includes 31 first date indicator tooth portions formed as inner teeth, and four calendar feeding teeth formed as inner teeth. The calendar feeding teeth consist of a first calendar feeding tooth serving as a reference, a second calendar feeding tooth, a third calendar feeding tooth, and a fourth calendar feeding tooth; each calendar feeding tooth is equipped with a normal rotation feeding portion for feeding the first date indicator in a first direction, and a reverse rotation feeding portion for feeding the first date indicator in a second direction opposite to the first direction (See JP-A-2005-214836).
(2) Second Type Conventional Calendar Mechanism
A second type conventional calendar mechanism has a scale with four positions of “0” to “3” plus a blank, or “1” to “3” plus a blank, and includes a member advancing each 10 days to indicate the ten place, and a member advancing each 24 hours to indicate the one place. The member indicating the one place can assume 31 positions, and three scales on which the numbers “0” to “9” are successively arranged are successively mounted thereto. In one of the scales, an additional “1” is inserted between the numbers “0” and “1” (See Japanese Patent No. 4307613).
(3) Third Type Conventional Calendar Mechanism
A third type conventional calendar mechanism is equipped with a dial with a large window, and a one-place rotary member (i.e., the first date indicator) on which there are arranged 31 numbers including one number “1” and three sets of numbers “1” to “9” and “0” and which is equipped with four teeth; further, it is equipped with a ten-place star-shaped plate having four teeth, and a ten-place rotary member (i.e., the second date indicator) on which the numbers “0”, “1”, “2” and “3” are arranged. The one-place rotary member (i.e., the first date indicator) directly rotates the ten-place rotary member (i.e., the second date indicator) (See Japanese Patent No. 3390021).
(4) Fourth Type Conventional Calendar Mechanism
A fourth type conventional calendar mechanism is equipped with a rotary disc on which the successive numbers of “0” to “9” are arranged on a peripheral edge ring and which indicates the one place of a date, and a rotary disc on which the numbers “0”, “1”, “2”, “3” and “3” arranged in that order are arranged on a peripheral edge ring and which indicates the ten place of a date. On the night of the 9th day, on the night of the 19th day, on the night of the 29th day, on the night of the 30th day and on the night of the 31st day, the rotary disc indicating the ten place of a date moves from the position at that point in time to the next position. On the night of every day except for the 31st day, the rotary disc indicating the one place of a date moves from a position to the next position (See Japanese Patent No. 4324550).
(5) Fifth Type Conventional Calendar Mechanism
A fifth type conventional calendar mechanism is equipped with a first indicating device indicating the one place of a date, and a second indicating device indicating the ten place of a date. The first indicating device and the second indicating device are driven by a program gear set, and a date wheel advances one step. During date change, the date wheel of the program gear set is driven by the peak of a lever. During the period of date change, the peak is engaged with the portion of the date wheel between first and second teeth. When date change occurs, the peak is disengaged from the first and second teeth of the date wheel, and gets between the second and third teeth of the date wheel, with the date wheel advancing one step (See JP-T-2009-531650).
(6) Sixth Type Conventional Calendar Mechanism
In a sixth type conventional calendar mechanism, a first moving member indicates the one place of a date, and complete dates of 1 through 9, and a second moving member indicates the ten place of a date, and complete 30th and/or 31st date. The moving member of a one-place ring is equipped with a driving protrusion. Due to this driving protrusion, it is possible to operate the moving member of a ten-place ring (See JP-T-2006-522323).
(7) Seventh Type Conventional Calendar Mechanism
A seventh type conventional calendar mechanism is equipped with a normal ten-place scale indicating a ten-place number solely through a ten-place date display hole, and a double display scale displaying a ten-place number through a ten-place date display hole and displaying a one-place number through a one-place date display hole. A one-place date plate is equipped with five ten-place drive teeth. A ten-place date indicator is rotated by the ten-place drive teeth (See JP-A-2009-250912).
In conventional timepieces with a calendar mechanism including a first date indicator and a second date indicator, the structure of the calendar mechanism is rather complicated and has a rather large thickness. Further, in conventional timepieces with a calendar mechanism including a first date indicator and a second date indicator, it is rather difficult to increase the size of the date letters of the first date indicator and of the date letter of the second date indicator. Further, in conventional timepieces with a calendar mechanism including a first date indicator and a second date indicator, to produce a timepiece with a calendar mechanism, there is involved a change on a rather large scale in the movement constituting the base.